java - 是否可以使用 AssistedInject 来注入(inject)构造函数之外的成员？

Question

我想做这样的事情:

@Inject private CollectorsListHolderFactory collectorsListHolderFactory;
private CollectorsListHolder collectorsListHolder;
private String projectName;
private NodeInfo node;

@Inject
public CollectorsRunner(@Assisted String projectName, @Assisted NodeInfo node) {
    super();
    this.projectName = projectName;
    this.node = node;
    collectorsListHolder = collectorsListHolderFactory.create(projectName, node);
}

但是我得到了NullPointerException，因为collectorsListHolderFactory是null。是否可以在不使用构造函数的情况下注入(inject)该成员？

Answer 1

辅助注入(inject)很乐意注入(inject)字段，与 Guice 的其余部分相同，但它发生在调用构造函数之后。 (毕竟，它需要先创建实例，然后才能设置其字段。)您可以这样做:

private final String projectName;
private final NodeInfo node;
private CollectorsListHolder collectorsListHolder;

@Inject
public CollectorsRunner(@Assisted String projectName, @Assisted NodeInfo node) {
    this.projectName = projectName;
    this.node = node;
}

@Inject
void injectCollectorsListHolderFactory(CollectorsListHolderFactory factory) {
    this.collectorsListHolder = factory.create(projectName, node);
}

但如果可以的话，你应该avoid public injectable constructors完全。